The user-written USER-FORMAT-ROUTINE performs format operations.
The symbiont's control logic routine calls your format routine
at one of two possible points within the symbiont's execution
stream. You select this point by specifying one of two routine
codes when you call the PSM$REPLACE routine.
A user format routine can be an input filter routine (routine
code PSM$K_INPUT_FILTER) or an output filter routine (routine
code PSM$K_OUTPUT_FILTER). The main format routine (routine code
PSM$K_MAIN_FORMAT) cannot be replaced.
A user format routine must use the call interface described here.
Format
USER-FORMAT-ROUTINE request_id ,work_area ,func ,func_desc_1
,func_arg_1 ,func_desc_2 ,func_arg_2
1 – Returns
OpenVMS usage:cond_value
type: longword (unsigned)
access: write only
mechanism: by value
Longword condition value. Most utility routines return a
condition value in R0. Condition values that this routine can
return are listed under Condition Values Returned.
2 – Arguments
request_id
OpenVMS usage:address
type: longword (unsigned)
access: read only
mechanism: by reference
Request identifier supplied by the symbiont when it calls your
format routine. The request_id argument is the address of a
longword containing this request identifier value.
work_area
OpenVMS usage:address
type: longword (unsigned)
access: write only
mechanism: by reference
Work area supplied by the symbiont for the use of your format
routine. The symbiont supplies the address of this area when
it calls your routine. The work_area argument is a longword
containing the address of the work area. The work area is a
section of memory that your format routine can use for buffering
and other internal operations.
The size of the work area allocated is specified by the work_size
argument in the PSM$PRINT routine. If you do not specify work_
size in the call to PSM$PRINT, no work area is allocated.
In a multithreaded symbiont, a separate work area is allocated
for each thread. This work area is shared by all user routines.
The work area is initialized to zero when the symbiont is first
started.
func
OpenVMS usage:function_code
type: longword (unsigned)
access: read only
mechanism: by reference
Function code specifying the service that the symbiont expects
your format routine to perform. The func argument is the address
of a longword into which the symbiont writes this function code.
The function code specifies the reason the symbiont is calling
your format routine or, in other words, the service that the
symbiont expects your routine to perform at this time.
The PSM$K_FORMAT function code is the only one to which your
format routine must respond. When the symbiont calls your format
routine with this function code, your routine must move a record
from the input buffer to the output buffer.
The symbiont can call your format routine with other function
codes. Your routine should return the status PSM$_FUNNOTSUP
(function not supported) when it is called with any of the
following function codes or with any undocumented function code.
When the status PSM$_FUNNOTSUP is returned, the symbiont performs
its normal action as if no format routine were supplied. To
suppress the symbiont's normal action, you should return SS$_
NORMAL.
PSM$K_START_STREAM PSM$K_STOP_STREAM
PSM$K_START_TASK PSM$K_PAUSE_TASK
PSM$K_RESUME_TASK PSM$K_STOP_TASK
PSM$K_RESET_STREAM
These function codes correspond to message items sent by the job
controller to the symbiont.
Other function codes correspond to internal symbiont mechanisms
that are not part of the public interface to the print symbiont.
Your format routine should return the status PSM$_FUNNOTSUP or
SS$_NORMAL when it is called with a message function code or with
a private function code.
func_desc_1
OpenVMS usage:char_string
type: character string
access: read only
mechanism: by descriptor
Descriptor supplying an input record to be processed by the
format routine. The func_desc_1 argument is the address of a
string descriptor. By using this argument, the symbiont supplies
the input record that your format routine is to process. Because
this descriptor can be of any valid string type, your format
routine should use the Run-Time Library string routines to
analyze this descriptor and to manipulate the input record.
func_arg_1
OpenVMS usage:vector_byte_unsigned
type: byte (unsigned)
access: read only
mechanism: by reference
Carriage control for the input record supplied by func_desc_
1. The func_arg_1 argument is the address of a 4-byte vector
that specifies the carriage control for the input record. The
following diagram depicts the format of this 4-byte vector:
31 23 15 7 0
-----------------------------------------------------
| Character | Count | Character | Count |
-----------------------------------------------------
Trailing Carriage Leading Carriage
Control Information Control Information
Bytes 0 and 1 describe the leading carriage control to apply
to the input data record; bytes 2 and 3 describe the trailing
carriage control.
Byte 0 is a number specifying the number of times the carriage
control specifier in byte 1 is to be repeated preceding the
input data record. Byte 2 is a number specifying the number of
times the carriage control specifier in byte 3 is to be repeated
following the input data record.
For values of the carriage control specifier from 1 to 255, the
specifier is the ASCII character to be used as carriage control.
Value 0 represents the ASCII "newline" sequence. Newline consists
of a carriage return followed by a linefeed.
The func_arg_1 argument is not used if your format routine is an
output filter routine (routine code PSM$K_OUTPUT_FILTER). See the
Description help topic for more information.
func_desc_2
OpenVMS usage:char_string
type: character string
access: write only
mechanism: by reference
Descriptor of a buffer to which your format routine writes the
formatted output record. The func_desc_2 argument is the address
of a string descriptor.
Your format routine must return the formatted data record by
using the func_desc_2 argument.
Your format routine should use the Run-Time Library string
routines to write into the buffer specified by this descriptor.
func_arg_2
OpenVMS usage:vector_byte_unsigned
type: byte (unsigned)
access: write only
mechanism: by reference
Carriage control for the output record returned in func_desc_2.
The func_arg_2 argument is the address of a 4-byte vector that
specifies the carriage control for the output record. See the
description of func_arg_1 for the contents and format of this
4-byte vector.
If you do not process the carriage-control information supplied
in func_arg_1, then you should copy that value into func_arg_2.
Otherwise, the carriage-control information will be lost.
The func_arg_2 argument is not used if your format routine is an
output filter routine (routine code PSM$K_OUTPUT_FILTER). See the
Description for more information.
3 – Description
When used, the func_arg_1 argument describes carriage-control
information for the input data record, and the func_arg_2
argument describes carriage-control information for the output
data record.
The input data record is passed to the format routine (input
filter or output filter) for processing, and the output data
record is returned by the format routine (input filter or output
filter).
One of the tasks performed by the main format routine (routine
code PSM$K_MAIN_FORMAT) is that of embedding the carriage-control
information (specified by func_arg_1) into the data record
(specified by func_desc_1). Thus, the output data (specified
by func_desc_2) contains embedded carriage control and is thus no
longer in record format; it is, therefore, properly referred to
as an output data stream rather than an output data record.
Similarly, the output filter routine (routine code PSM$K_OUTPUT_
FILTER), which executes after the main format routine, uses
neither the func_arg_1 nor func_arg_2 argument; the data it
receives (via func_desc_1) and the data it returns (via func_
desc_2) are data streams, not data records.
However, the input filter routine (routine code PSM$K_INPUT_
FILTER), which executes before the main format routine, uses
both func_arg_1 and func_arg_2. This is so because the main
format routine has not yet executed, and so the carriage control
information has not yet been embedded in the data record.
4 – Condition Values Returned
SS$_NORMAL Successful completion. The user format routine
has completed the function that the symbiont
requested.
PSM$_FUNNOTSUP Function not supported. The user format
routine does not support or does not recognize
the function code supplied by the symbiont.
To ensure future compatibility, your format
routine should return this status for any
unrecognized status codes.
This routine also returns any error condition values that you
have coded your format routine to return.